The measurement of lightning currents in direct strokes

The magnitude and wave shape of the discharge currents in 46 direct strokes have been measured during a five-year period at 25 direct-stroke stations on structures ranging in height from 75 to 585 feet. Measurements have been made with instruments capable of recording the wave front and tail of the high-current peaks and the low-magnitude continuing currents to as low as 0.1 ampere. These data are correlated with 138 special camera photographs of strokes to open ground obtained in this investigation, with similar photographs taken in South Africa and with stroke current measurements made on the Empire State Building in New York City.